Crude oils and residual fuel oils containing a terpolymer of ethylene, vinyl ester, and dialkylvinyl carbinol

ABSTRACT

Crude oils and residual fuel oils having improved pour point and flow properties are obtained by incorporating therein a small amount of a new terpolymer prepared from ethylene, a vinyl ester, and a dialkylvinyl carbinol. The terpolymer has a number average molecular weight of about 500-10,000 and suitably contains 45-80 wt. % ethylene, 10-25 wt. % vinyl ester of a fatty acid having up to about eight carbon atoms and 10-30 wt. % dialkylvinyl carbinol wherein the alkyl groups have up to about six carbon atoms.

United States Patent Basalay et al. Oct. 28, 1975 CRUDE OILS AND RESIDUAL FUEL OILS 3,575,893 4/1971 Buysch et al. .1 260/80.75 CONTAINING A TERPOLYMER OF 3,854,893 12/1974 Rossi 44/62 ETHYLENE, VINYL ESTER, AND DIALKYLVINYL CARBINOL Primary Examiner-Daniel E. Wyman Assistant Examiner-'V. H. Smith [75] Inventors. Robert J. Basalay, Napervllle, Peter Attorney, g or Firm Phmp Arthur G G. Pappas, Downers Grove, Walter Glk T M C] C. Edmisten, Olympia Fields, all of 1 1 lam C am [11.

[73] Assignee: Standard Oil Company, Chicago, Ill. [57] ABSTRACT Filedi 1974 Crude oils and residual fuel oils having improved pour [21] AppL NO; 522,471 point and flow properties are obtained by incorporatlng therem a small amount of a new terpolymer prepared from ethylene, a vinyl ester, and a dialkylvinyl U-S. cafbinoL The terpolymer has a number average mo- [51] Int. Cl. ClOL 1/18 le ular weight of about SOC-10,000 and suitably con- Fleld of Search 260/8075, tains 45-80 wt. ethylene, 1025 wt. vinyl ester of a fatty acid having up to about eight carbon atoms and 10-30 wt. dialkylvinyl carbinol wherein the alkyl [56] R fer n s C t d groups have up to about six carbon atoms.

UNITED STATES PATENTS 3,467,597 9/1969 Tunkel et al 44/62 3 Drawmgs 1 CRUDE OILS AND RESIDUAL FUEL OILS CONTAINING A TERPOLYMER OF ETI-IYLENE, VINYL ESTER, AND DIALKYLVINYL CARBINOL BACKGROUND OF THE INVENTION Crude oils and heavier fractions such as residual fuel oils contain substantial quantities of waxy material. When such oils are subjected to low temperatures, the waxy material crystallizes into long needles or platelets that agglomerate into a gel-like matrix. Crystallization of waxy material in this manner interferes with the free flow of oil and causes serious distribution and operating difficulties. For example, pumping from producing wells and from storage in tanks and transport through pipelines at low temperatures are difficult or impossible. In heating systems, flow through filters cannot be maintained with the result that the heating equipment fails to function.

The aforementioned difficulties have been remedied in part by addition of known pour point .depressants. The pour point of an oil is defined as the lowest temperature at which the oil will flow when it is chilled without disturbance under specified conditions. The pour point so determined provides a measure of the lowest temperature permissible during storage, transport, or use of the oil. Pour depressants are essentially wax crystal modifiers. If upon cooling of the oil the solubility of the pour depressant is such that it comes out of solution before the wax, the depressant may act as a nucleating agent and promote the formation of small wax crystals that are less capable of forming a gel. If the depressant and wax come out of solution together, they may cocrystallize into bulky crystals that have a lower tendency to form a rigid gel. If thedepressant comes out of solution after the wax, precipitation on the surface of the normally-formed wax crystals may inhibit the adhesion necessary to form a gel.

Recently, certain polymeric products have been made and proposed as pour point depressants in certain oils, particularly in distillate fuel oils. While effective in distillate fuel oils such known polymeric products generally are not sufficiently effective in residual fuels or in waxy crude oils. For example, US. Pat. No. 3,048,479 discloses copolymers of ethylene and vinyl acetate as pour point depressants for middle distillate fuel oils; however, such copolymers are marginally or not at all effective in residual fuel oils or .in crude oils. Other such copolymers-in the field are. illustrated by the following patents: US. Pat. Nos. 2,499,723; 2,654,188; 3,093,723; 3,126,364; 3,236,612 and others.

The state of the art is further illustrated by the following patents. US. Pat. No. 3,447,915 teaches the use of terpolymers of ethylene, propylene, and an alkyl ester of acrylic acid or methacrylic acid as pour point depressants in fuel oils. The pour point depressant and flow improvers disclosed in US. Pat. No. 3,467,597 are terpolymers of ethylene, vinyl esters, e.g., vinyl acetate, and a mono-olefinically unsaturated polymerizable compound grafted with ethylene. US. Pat. No. 3,679,380 discloses middle distillate fuel compositions containing a terpolymer of ethylene, propylene, and 1,4-hexadiene as pour point depressants to facilitate the movement of waxy crude oil through pipelines.

SUMMARY OF THE INVENTION This invention is directed to new terpolymers that are effective in lowering pour point and improving flow properties of crude oils and residual fuel oils are prepared by copolymerizing ethylene, a vinyl ester of a fatty acid having up to about eight carbon atoms, and a dialkylvinyl carbinol, wherein the alkyl groups have up to about six carbon atoms, in the presence of a free rad- .ical catalyst. Suitably, the aforementioned monomers are copolymerized under conditions such that a terpolymer is produced containing about 45-80 wt. ethylene, 10-25 wt. of the vinyl ester, and 10-30 wt. 7c of the dialkylvinyl carbinol, and having a number average molecular weight in the range of about 500-10,000, preferably about 2,0002,500. Within this relatively low molecular weight range we have found that our terpolymers possess unexpectedly high flow improvement activity. In contrast, such prior art products as ethylene-vinyl acetate copolymers must be prepared with number average molecular weights of about 10,000, and preferably about 25,000 in order to exhibit effective pour point lowering properties. Furthermore, the terpolymers of this invention, being of lower molecular weight, have lower viscosities and thus offer the advantages of better low temperature storage and handling properties and easier blending into oil stocks.

Methods for copolymerizing olefinic monomers in the presence of free radical catalysts are well known in the art. The copolymerization reaction can be carried out in solution, in emulsion, or in the vapor phase under a wide range of reaction temperatures and pressure and with a wide variety of free radical catalysts. Examples of free radical catalysts that can be used are azo-nitriles such as azo-bis-isobutyronitrile; alkyl peroxides such as t-butyl peroxide; acyl peroxides such as benzoyl peroxide; ketone peroxides such as methylethyl ketone peroxide; hydroperoxides such as cumene hydroperoxide; and peresters such as t-butyl perbenzoate. Generally, for a given reaction temperature a catalyst is selected that generates free radicals at a rate such that the polymerization reaction is readily controllable.

For the preparation of our terpolymers the vinyl ester and the dialkylvinyl carbinol are preferably dissolved in an inert solvent such as benzene. The reaction vessel is flushed with ethylene and heated to a reaction temperature of about -l 50C, preferably about lO5C. Ethylene is then pressured into a reaction vessel to a pressure of about 500-1 ,500 psi, preferably about 1,000-l,200 psi. About 0.1-5 wt. 7c, preferably about 1.0-2.0 wt. of a catalyst such as azo-bis-isobutyronitrile is then added and the reaction mixture is held at reaction temperature for about 0.5-2 hours, suitably about 1 hour. The reaction mixture is then cooled, the pressure is reduced, solvent and unreacted monomers are separated by distillation, and the desired terpolymer is obtained.

The terpolymers so produced are effective in lowering pour point and improving flow properties of crude oils and residual fuel oils when added thereto in .amounts of from about 0.001 wt. 7: to about 5 wt. 72,

preferably from about 0.0025 wt. 7c to about 1 wt. 76. Residual fuel oils are topped crude oils. For example, an atmospheric residual fuel oil is obtained by distillation of crude oil at atmospheric pressure to a specified end-point temperature, usually about 650F. Re-

sidual fuel oils that can be employed in the practice of the present invention are further defined in ASTM Designation D-396 as No. 4, No. 5, and No. 6 fuel oils. Such oils have viscosities that fall in the range of from about 45 Saybolt Seconds Universal at F to 300 Saybolt Seconds Furol at 122F. Oils treated with our terpolymer may also contain other additives; for example, corrosion inhibitors, anti-oxidants, rust inhibitors, detergents, etc.

Our terpolymers, for convenience, may be prepared as addition agent concentrates. Accordingly, the terpolymers may be dissolved in a suitable organic solvent therefor in amounts greater than 5 wt. and preferably TABLE II FLOW IMPROVING PROPERTIES OF ETHYLENE,

VINYL ACETATE, AND DIMETHYLVINYL CARBINOL TERPOLYMERS Tcrpolymcr Sample Pour Point, "F

in Resid A(75)' 5, l l0 5 20 I5, IO l0 I5, 20 30 20. 25 40 60 in Resid B( 100) I00 85, 95 80. 75 80. 75

in Crude A( 10) 20 30 -25 25 Domestic Atmospheric Residual Oil having a pour point of +75F. -Nigerian Atmospheric Residual Oil having a pour point of +100F. Brut Arzew Yugoslavian crude oil having pour point of +10F.

about 2575 wt. The solvent in such concentrates preferably has a distillation range of from about 100F to about 700F. Suitable organic solvents are hydrocarbon solvents, for example, petroleum fractions such as naphtha, kerosene, heater oil, and the like; aromatic hydrocarbons such as benzene, xylene, and toluene; or paraffinie hydrocarbons such as hexane, octane, etc. The solvent employed should, of course, be selected with regard to the possible beneficial or adverse effects it may have on the final oil composition. Thus, the solvent used should preferably bum without leaving an objectionable residue, and should be non-corrosive with regard to metals.

PREFERRED EMBODIMENTS OF THE INVENTION The following examples are illustrative of this invention.

Terpolymers of ethylene, vinyl acetate and dimethylvinyl carbinol, listed in Table I, were prepared as follows:

1. A one-liter autoclave was charged with 300g of benzene solution containing the weight percent of monomers indicated in the Table.

2. The autoclave was flushed with ethylene, heated to 100C, and pressurized to 1,200 psig with ethylene.

3. A benzene solution containing 2.0% of azo-bisisobutyronitrile was added at a rate of 1 ml/minute for 25 minutes.

4. The reaction mixture was heated to 100C and then held at 100C for one hour.

5. The pressure was thereafter reduced and the reaction mixture was stripped of benzene solvent and other volatile components to yield about 10g of terpolymer.

TABLE I TERPOLYMERS OF ETHYLENE. VINYL ACETATE. AND DIMETHYLVINYL CARBINOL Although the present invention has been described with reference to certain specific preferred embodiments thereof, the invention is not limited thereto, but includes within its scope such modifications and variations as come within the scope and spirit of the appended claims.

We claim:

l. An oil composition, having improved pour point and flow properties, comprising a major portion of an oil, selected from the group consisting of crude oil and residual fuel oil, and from about 0.001 wt. to about 5 wt. of the terpolymer composition consisting of 4580 wt. ethylene, l025 wt. vinyl ester of a fatty acid having up to about eight carbon atoms, and 10-30 wt. of a dialkylvinyl carbinol wherein the alkyl groups have up to about six carbon atoms, said terpolymer having a number average molecular weight in the range of from about 500 to about 10,000.

2. A residual fuel oil composition, having improved pour point and flow properties, comprising a major portion of residual fuel oil and from about 0.01 wt. to about 0.1 wt. of a terpolymer consisting of about 5570 wt. ethylene, about 15-25 wt. dimethylvinyl carbinol, and about 1520 wt. vinyl acetate, and having a number average molecular weight of about 2,0002,500.

3. An addition agent concentrate composition for addition to crude oils and residual fuel oils to improve pour point and flow properties at low temperatures, comprising a hydrocarbon solvent boiling at a temperature in the range of from about F to about 700F and more than 5 wt. of the terpolymer composition consisting of 45-80 wt. ethylene, 10-25 wt. vinyl ester of a fatty acid having up to about eight carbon atoms, and 10-30 wt. of a dialkylvinyl carbinol wherein the alkyl groups have up to about six carbon atoms, said terpolymer having a number average molecular weight in the range of from about 500 to about 10,000, said concentrate being capable of dilution with crude oils and with residual fueLoils to produce compositions having improved pour and flow properties and containing from about 0.001 wt. 7: to about 5 wt. of said terpolymer. 

1. AN OIL COMPOSITION, HAVING IMPROVED POUR POINT AND FLOW PROPERTIES COMPRISING A MAJOR PORTION OF AN OIL, SELECTED FROM THE GROUP CONSISTING OF CRUDE OIL AND RESIDUAL FUEL OIL, AND FROM ABOUT 0.001 WT. % TO ABOUT 5 WT. % OF THE TERPOLYMER COMPOSITION CONSISTING OF 45-80 WT. % ETHYLENE, 10-25 WT. % VINYL ESTER OF A FATTY ACID HAVING UP TO ABOUT EIGHT CARBON ATOMS, AND 10-30 WT. % OF A DIALKYLVINYL CARBINOL WHEREIN THE ALKYL GROUPS HAVE UP TO ABOUT SIX CARBON ATOMS, SAID TERPOLYMER HAVING A NUMBER AVERAGE MOLECULAR WEIGHT IN THE RANGE OF FROM ABOUT 500 TO ABOUT 10,000.
 2. A residual fuel oil composition, having improved pour point and flow properties, comprising a major portion of residual fuel oil and from about 0.01 wt. % to about 0.1 wt. % of a terpolymer consisting of about 55-70 wt. % ethylene, about 15-25 wt. % dimethylvinyl carbinol, and about 15-20 wt. % vinyl acetate, and having a number average molecular weight of about 2,000-2,500.
 3. An addition agent concentrate composition for addition to crude oils and residual fuel oils to improve pour point and flow properties at low temperatures, comprising a hydrocarbon solvent boiling at a temperature in the range of from about 100*F to about 700*F and more than 5 wt. % of the terpolymer composition consisting of 45-80 wt. % ethylene, 10-25 wt. % vinyl ester of a fatty acid having up to about eight carbon atoms, and 10-30 wt. % of a dialkylvinyl carbinol wherein the alkyl groups have up to about six carbon atoms, said terpolymer having a number average molecular weight in the range of from about 500 to about 10,000, said concentrate being capable of dilution with crude oils and with residual fuel oils to produce compositions having improved pour and flow properties and containing from about 0.001 wt. % to about 5 wt. % of said terpolymer. 